Python csv.reader: How do I return to the top of the file?

Question

When I’m moving through a file with a csv.reader, how do I return to the top of the file. If I were doing it with a normal file I could just do something like “file.seek(0)”. Is there anything like that for the csv module?

Thanks ahead of time 😉

Asked By: Nope

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Source

Answer 1

You can still use file.seek(0). For instance, look at the following:

import csv
file_handle = open("somefile.csv", "r")
reader = csv.reader(file_handle)
# Do stuff with reader
file_handle.seek(0)
# Do more stuff with reader as it is back at the beginning now

This should work since csv.reader is working with the same.

Answered By: Evan Fosmark

Answer 2

You can seek the file directly. For example:

>>> f = open("csv.txt")
>>> c = csv.reader(f)
>>> for row in c: print row
['1', '2', '3']
['4', '5', '6']
>>> f.seek(0)
>>> for row in c: print row   # again
['1', '2', '3']
['4', '5', '6']

Answered By: Federico A. Ramponi

Answer 3

I’ve found the csv.reader and csv.DictReader a little difficult to work with because of the current line_num. making a list from the first read works well:

>>> import csv
>>> f = open('csv.txt')
>>> lines = list( csv.reader(f) ) # <-- list from csvReader
>>>
>>> for line in lines:
...  print(line)
['1', '2', '3']
['4', '5', '6']
>>>
>>> for line in lines:
...  print(line)
['1', '2', '3']
['4', '5', '6']
>>>
>>>lines[1]
['4', '5', '6']

this captures the optional first row used by the dictReader but lets you work with the list again and again and even inspect individual rows.

Answered By: Marc Compere

Python csv.reader: How do I return to the top of the file?

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